“Understanding Failover Clusters” was all about the why, what and where of it. In this article we shall look at the ‘How’ of setting up a failover cluster.

If your organization is proposing to upgrade to Microsoft SQL Server 2005 or to upgrade its servers from a previous version of SQL Server, the Installation Wizard that comes with SQL Server 2005 is a great boon. It makes the process a breeze. All you need to do is run the Wizard which is installer based. The installer has a single feature tree for the process of installation and you are guided through it step by step till you are done! Moreover, you do not have the hassle of installing the different components individually.

However, much as you would love to get going with the installation, there are certain preliminary checks you need to do to ascertain before you actually get down to initiating the set up process.

Checking for the availability of minimum hardware and software

The first step is to identify the platform on which you will install the failover cluster and the availability of the minimum hardware and software requirements. You will require:

A VGA or higher resolution monitor ( at least 1,024 x 768 pixel resolution)

A Microsoft mouse or a compatible pointing device.

A CD or DVD drive

The nodes that will form the cluster(Maximum of eight)

2.0 GB of hard disk space at the minimum.

If you have the minimum hardware requirements at hand, you will have to check on the minimum software requirements. These include:

Network software requirements (same for both 32 bit and 64 bit). If you are using Windows Server 2003, Windows XP or Windows 2000 you will find that they have built in network software.

If you have been connecting with Banyan VINES sequenced Packet Protocol (SPP), multiprotocol, Apple Talk or NWLink IPX/SPX, you will find that they are no longer useful to you. You need to select a different protocol to connect to SQL Server 2005.

The network protocols supported by stand alone, named or default instances include shared memory, named pipes, TCP/IP and VIA.However, failover clusters do not support shared memory.

Internet connectivity and browser software; Internet Information Services (IIS) 5.0 or later; ASP.NET 2.0

Microsoft Windows Installer 3.1 or later

Microsoft Data Access Components (MDAC) 2.8 SPI.

Microsoft .NET Framework 2.0(automatically installed while installing SQL Server 2005 Editions other than Express Edition)

Microsoft SQL Server Native Client (automatically installed while installing SQL Server 2005 Editions other than Express Edition)

Microsoft SQL Server Setup support files (automatically installed while installing SQL Server 2005 Editions other than Express Edition)

.NET Framework 2.0 Software development Kit (SDK) is optional. It contains the documentation, a C++ compiler and several other tools which may be useful while using the .NET framework for SQL Server development.

The SQL Server 2005 set up examines the system for existence of all the above software before commencing the installation. The installation will be unsuccessful if any or even one of the software components fail to install. The Software parameter check will verify and tell you if one or more of the components are missing.  You will have to ensure that it is available before you proceed any further.

Getting on with Failover Clusters pre-installation checks

SQL Server 2005 failover clusters require Microsoft Cluster Server (MSCS) to be installed at least on one of the nodes in the cluster. The hardware compatibility for this installation will have to be thoroughly tested and the hardware deployed must be in accordance with the cluster/ multi cluster device category of the Microsoft Windows catalog and hardware compatibility list. If geographically dispersed nodes are being clustered, the hardware solution must be on the Geographic Cluster Hardware compatibility list. SAN configurations are also supported and the set of SAN capable devices are listed in the Cluster/Multi cluster devices lists. Quorum disk resource sharing should also be considered to act as a tie breaker if all network communication between the cluster’s nodes fail.

Before installing the failover cluster instance, it is important to also check that the operating system is properly installed and will support the failover clustering. It is necessary to enable Windows Cryptographic Service Provider (CSP) on Windows Server 2003. The task scheduler will have be enabled on all the operating systems for remote can cluster installations. It should also be remembered that the number of clusters is limited to the number of letters available for assignment to the drives. It may be a good idea to use only one drive letter for the operating system and all other drive letters are made available as normal cluster drives or cluster drives hosting mount points (up to a maximum of 25 instances per failover cluster).

Care should also be taken to ensure that the base drive is the clustered drive. This drive cannot be shared among failover cluster instances. However, in stand alone, multi instance servers this restriction is not applicable.

The base drive and the mounted disks are listed as resources in the resource group. SQL Server setup does not automatically list them. It will also not check for the listing during the CREATE/ ALTER DATABASE procedure.

The mounted disks or volumes are mounted under the correct lettered base drive and all mounted drives should be set up as dependent on the parent drive.

Microsoft Cluster Server(MSCS) is configured on at least one node of the server cluster and the hardware configuration has been tested for compatibility with the MSCS software.

The failover cluster instance is active and running. This can be done by using the IsAlive thread by connecting to the server using a trusted connection. The permissions on the cluster nodes are to be changed from the default BUILTIN\Administrators group permission or the IsAlive check will fail.

Separate service accounts are set up to log on to MSCS and to SQL Server since the cluster password cannot be changed using the cluster command.

The control of the shared SCSI bus is with one node before the second node comes alive else the application failover will go into an online pending state and prevent the failover into another node. Wherever the proprietary process exists the same should be used.

The Microsoft Distributed Transaction Coordinator (MSDTC) cluster resource is created on Windows 2000 or Windows Server 2003 if the Database Engine and SSIS Notification Services or Workstation components are being installed. Availability can also be ensured by configuring the MSDTC to have its own resource group. Failing this, the Cluster group and Quorum drive should be used for this purpose.  While absence of this will not block the SQL Server set up, it will impact the functionality adversely.

Other software considerations are also taken into account such as the configuration of the COM+, disk drive letters, users in the  Administrators group, the cluster interconnect configuration, cleaning of system logs and so on.

Network Considerations for failover clustering setup would include:

Disabling NetBIOS of all private network cards before set up of SQL Server.

Ensuring that the IP Address and name of the SQL Server is not being used for any other purpose on the network such as file sharing.

Once you have completed all the above checks, you will need to log on to the Server as a service with local administrator permissions and perform the actions of the operating system on all the nodes of the failover cluster instance. You will need to disable all applications and services that may use SQL Server components. You will also have to create domain groups for cluster services that will be installed. The Domain Name Service (DNS) or Windows Internet Name Service will have to be configured to run in the environment in which the failover cluster server will be installed. The SQL Server Setup requires a dynamic domain name service (DDNS) registration and will fail if it does not exist. Finally you will also have to consider whether the tools, features and components you propose to use are supported with failover clustering.

As is evident from the above, the process of installing the failover cluster is not an easy one. However, due diligence in the preparatory phase will yield rich dividends.Bottom of Form